Integrated circuits (ICs), such as complementary metal-oxide-semiconductor (CMOS) radio frequency integrated circuit (RFIC), often employ passive components, such as resistors, capacitors, or inductors. Inductors may include planar spiral inductors made of metal wires disposed on surface of a substrate or a dielectric layer of an IC device. Planar spiral inductors typically have low noise and low power consumption and are easy for device integration with low cost. With downsizing of IC devices, there are challenges on process uniformity and stability.
FIGS. 1-2 depict a conventional inductor device. Specifically, FIG. 2 shows a top view of the inductor device. FIG. 1 shows a cross section along A-A′ line of the device shown in FIG. 2.
As shown in FIG. 1, the device includes a spiral wiring 102 disposed on a dielectric layer 101. The dielectric layer 101 is disposed on a semiconductor substrate 100. The spiral wiring 102 has three rounds (or turns) of a metal wire with an inner radius of 45-50 μm. The metal wire has a width of 8-10 μm. The spiral wiring 102 has one end connected to an input contact point (pad) 103 and the other end connected to an output contact point (pad) 104 for current inputting and outputting of the device.
However, such planar inductor often has a low quality factor (Q), which may affect the performance of the planar inductor. There is a need to provide inductor devices with improved device quality factor and performance.